1. Field of the Invention
The present invention generally relates to a capacitive touch panel, and more particularly, to a capacitive touch panel with multilayer receiver mesh electrodes.
2. Description of the Prior Art
A touch panel can detect touch action on an active region or display region. For example, it can detect if the user touches a touch button having the form of an image by using fingers, or can detect the position of the fingers and their track. Certain touch panels may detect the touch action performed by the object other than fingers, such as the stylus pen which can generate digital signal, to perform more precise touch actions, writings or even drawings.
Nowadays the touch panel may have various technologies or types, such as resistive type, capacitive type, infrared type, or surface acoustic type. At present the capacitive touch-sensing is the most popular and mature touch technology, in which the principle lies in the change of capacitance value of the electrode in the panel when the object touches or closes the panel surface, and the touch position and its track can be calculated and determined through this capacitance change. In the past the sensing electrode of capacitive touch panel is usually made of tin-doped indium oxide (ITO). This material is quite expensive and has higher resistance, thus it is not a suitable material for the application of a large-size panel. So far many materials or technologies are developed in the industry to replace the use of ITO, such as the use of metal mesh, carbon nanotube (CNT), silver nanowire, grapheme and conductive polymer, etc. For the moment the technology of metal mesh is almost mature and can be run smoothly in mass production. It may be one of the candidates to replace traditional ITO electrode and sweep into the mainstream.
In spite of smooth development, there are still some process bottlenecks to break through. One of them is the problem of compatible control IC. The touch panel using metal mesh electrodes would require more touch-sensing channels than the one using other touch technology. This disadvantage is apparent under the application of large-size panels. For example, a 55-inch touch panel with 5 mm pitch spec may need 381 sensing channels, which is twice the number required in a 27-inch touch panel. This channel number is far beyond the ability of common control IC. Accordingly, the disadvantage of excessive sensing channels in metal mesh electrode is still an intractable problem for the developers in the art to deal with.